1. Field of the Invention
The present invention relates to aromatic polyester-polycarbonate resins. More particularly, the present invention relates to aromatic polyester-polycarbonate resins which have excellent mechanical properties, thermal stability, chemical resistance and transparency and which are suitable for the fabrication of articles by melt molding.
2. Description of the Prior Art
In the preparation of prior art aromatic polyester-polycarbonates, one resin which has been suggested is a copolymer which is produced by the reaction of 2,2-bis-(4-hydroxyphenyl)-propane-(bis-phenol A) with terephthaloyl chloride and phosgene. The copolymer has a bis-phenol A residue:terephthalic acid residue:carbonate moiety constituent mole ratio in the range of 2:0.8-1.3:1.2-0.7 and a glass transition point (Tg) in the range of from 170.degree. to 194.degree. C. (Japanese Patent Laid-Open Publication No. 128992/1977). Because of its high softening point and high melt viscosity, however, the polyester-polycarbonate product has not proved to have satisfactory moldability characteristics. When it is to be injection molded into a shaped article, for example, it must be molded at high temperature, metal-die temperature and injection pressure. The use of high temperatures has the disadvantage that thermal deterioration of the resin occurs. Moreover, the use of high injection pressure is disadvantageous because it distorts the shaped product. Still further, the use of elevated temperature and pressure increases the cost of preparation. Under these circumstances, a need has long been felt for polyester-polycarbonates of improved moldability.